<!DOCTYPE html>
<!-- Any copyright is dedicated to the Public Domain.
   - http://creativecommons.org/publicdomain/zero/1.0/ -->

<html>
  <style>
  div#details {
    background-color: orange;
    width: 500px;
    height: 200px;
  }
  div#summary {
    background-color: green;
    width: 50%;
  }
  div#in_summary {
    position: absolute;
    background-color: green;
    top: 60px;
    left: 100px;
    width: 150px;
    height: 100px;
  }
  div#before_summary {
    position: absolute;
    background-color: cyan;
    top: 50px;
    left: 50px;
    width: 150px;
    height: 100px;
    z-index: 1;
  }
  </style>
  <body>
    <div id="details">
      <div id="before_summary">div before summary</div>
      <div id="summary">Summary<div id="in_summary">div in summary</div></div>
    </div>
  </body>
</html>
